Skin creams of different kinds have been more and more popular and a lot of cosmetic companies are producing “miracle” creams. Scientists are quite aware of the necessity to “feed” the skin in different ways. Except from moistening factors, the skin needs also, as the whole body, nutrients as for instance vitamins, minerals, calories etc.
A number of new ointments or creams is introduced to the market each year, containing new agents believed to be good for the skin. However, it has been shown lately as reported in The Time (Aug. 28, 2000, pp. 34-38. Facelift in a jar.) that a number of these creams contains questionable ingredients and in amounts not meeting the amounts on the package leaflets.
The skin is the biggest organ of the human body and is very complex, due to its many functions. It should prevent the body from poisoning substances, which means it must have a strong barrier function. It should be able to sustain trauma of different kinds and if the skin is damaged it must be able to quickly repair itself. However, the skin is also sensitive to different factors such as, e.g., sun radiation which causes ageing of the skin. Many creams are on the market to protect against sunshine and others to reduce ageing of the skin, and a lot of research have been put into the fields of skin protection, skin reparation and anti-ageing.
Compounds that can feed the skin are fatty acids. Among them there is one recently discovered fatty acid called CLA (conjugated linoleic acid). The term CLA is a generic term used to reference both conjugated linoleic acid and conjugated linolenic acid. Since linoleic acid is an essential fatty acid, its conjugated forms are readily absorbed into lipids and fats. Theoretically, conversion of ordinary linoleic acid to conjugated linoleic acid results in eight isomers.
CLA is known to have several effects on different cell systems. In the body effects such as antioxidant effect, immune stimulant effect and antiallergenic effects are observed. Additionally CLA has been shown to promote cell generation in both animal and human subjects. It does also have effect on fat reduction and muscle building. For skin CLA could be an ideal substance to improve skin quality. However, due to its nature the major problem is to make it penetrate the skin and exert its effects directly in the skin.
Another nutrient is A-vitamin acid which has a well-documented effect on skin. In the cells A-vitamin acid has nutritional effects and promotes regeneration. However, this compound does also have side effects. Due to its irritant effect it can only be bought on prescription, and is used in certain skin diseases as acne, psoriasis, eczema and others. It is known that the fat-soluble vitamin A is harmless to the skin, and inert, but if it penetrates the skin cells it will immediately be hydrolysed to A-vitamin acid and can exert its beneficial effect without irritation. It has earlier been shown by Wadstein (1991) that vitamin A bound to a certain carrier (β-cyklodextrin) could penetrate the skin almost as effective as A-vitamin acid, but without the above mentioned side effects. Creams with this solution has successfully been sold for more than 10 years.
Bovien colostrum does also have a beneficial effect on the skin and can therefor be added to skin compositions. Colostrum concentrates normally contain IgG (gammaglobulin) which enhances fagocytosis; IgA which protects the mucosal surfaces; IgM which also enhance fagocytosis and is especially effective against micro-organisms; IgD which stimulates B-cells to produce antibodies and IgE which is associated with allergic reactions. Another important factor found in bovine colostrum is IGF-1 (growth factor) which is an important promoter of cell formation and promotes skin juvenation in skin compositions. The antibacterial effects of the immunoglobulins have a certain impact on the healing efficacy of the skin compositions, as it has been shown that bacterial infection occurs in 100% of eczema's and skin wounds.
Dryness of the skin is an other problem. Several substances (hydrogels) such as, for example, chitosan, carboxy methyl cellulose, cyclodextrins have been used to prevent this.
Chitosan is a deacetylated breakdown product of chitin which is one of the most abundant polymers in the nature after cellulose. Chitosan is prepared from chitin which for example may be produced from the waste in the shellfish industry where shrimps are processed. Chitin and chitosan both belong to the group of polysaccharides.
Chitosan has the properties of a gel and binds as such water and contributes to the moistening effect of the skin. As dryness of the skin is a major problem, the ability to bind water both treat and prevent this condition. Chitosan does also have an anti-microbial effect beginning at a concentration of about 0.4 wt % and upwards of the composition.
From the prior art several topical formulations for treatment of the skin comprising conjugated linoleic acid are known. WO-9932105 discloses a composition for topical use comprising CLA esters and a topical carrier. U.S. Pat. No. 6,019,990 discloses cosmetic formulations comprising a conjugated linoleic acid and an ester of conjugated linoleic acid. These formulations may also contain a UV absorbing compound. WO-0037040 describes a topical composition comprising (a) conjugated linoleic acid, and/or derivatives thereof comprising conjugated linoleic acid moieties, in which at least 50% by weight og the conjugated linoleic acid and/or moieties, is present as the cis 9 trans 11 and (b) a dermatologically acceptable carrier.
Also cosmetic preparations containing chitosan are known for example from U.S. Pat. No. 5,057,542 and Pittermann W. et al., Efficiency of high molecular weight chitosan in skin care applications in Chitin Handbook, R. A. A. Muzzarelli and M. G. Peter, eds., European Chitin Society, 1997.
Additionally cosmetic compositions containing both chitosan and linoleic acid are known form EP-A-414608, which discloses cosmetic compositions comprising chitosan, some glucosamine and at least one organic acid selected from gluconic acid and succinic acid. FR-2785179 describes cosmetic compositions containing a aqueous dispersion of particulate filmogenic polymers and a polyorganosiloxane polyester of the type dimethicone copolyol comprising ester groups derived from fatty acids of vegetable oils comprising mainly oleic acid. WO-9847487 discloses a drug delivery system containing a liquid crystalline phase and a reverse micellar liquid crystalline phase. U.S. Pat. No. 5,874,463 describes a hydroxy-kojic acid skin peel for treatment of hyperpigmentation, melasma, dyschromia, rhytides, photodamage and aging. And WO-9939700 discloses pharmaceutical compositions in form of nanoparticles comprising a composite material, consisting of at least one lipidic substance and of at least one amphiphilic substance and of a pharmaceutically active principle.